A method of ensuring high integrity of a processor is provided. The method includes executing sets of sequential instructions, each execution being based on a unique initial value, generating a computed final value responsive to each execution of a set of sequential instructions, and sending computed values to a monitoring portion of a high integrity processor monitor system responsive to the generating for each execution of the set of sequential instructions. The execution of the sets of sequential instructions tests pertinent addressing modes, operand sizes, and instruction side-effects for each instruction tested in a monitored central processing unit.